 Tang joined the Royal Hong Kong Police in 1976 as a Probationary Inspector.Prior to his promotion to a Superintendent in 1986, he served in divisions such as the Police Tactical Unit and the Special Duties Unit.Tang was promoted in 1992 to Senior Superintendent and posted as District Commander Airport, Chief Superintendent Special Duty for the 1997 Handover of Sovereignty Ceremonies, District Commander of Mongkok District, as well as Deputy Regional Commander of Hong Kong Island Region.